Events in the germ cell lineage after entry of the primordial germ cells into the genital ridges in normal and u.v.-irradiated Xenopus laevis

Development ◽  
1977 ◽  
Vol 41 (1) ◽  
pp. 33-46
Author(s):  
Brigitta Züst ◽  
K. E. Dixon
Keyword(s):  
Xenopus Laevis ◽  
Germ Cell ◽  
Germ Cells ◽  
Dorsal Root ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Cell Stage ◽  
Comparison Of The Results ◽  
New Generation

Approximately 20–25 primordial germ cells leave the endoderm between stages 38–41 and localize in the dorsal root of the mesentery by stage 43/44. At this time all the cells contain large quantities of yolk which is gradually resorbed. The cells begin dividing between stages 48–52. The number and size of the germ cells were measured in tadpoles between stages 48–54 of development. The results indicate that in females the germ cells divide more often than in males. In both sexes the mitoses are grossly unequal, leading to the formation of a new generation of germ cells which are considerably smaller (one-tenth to one-fifth) than the size of the primordial germ cells at stage 48. The germ cells in male tadpoles at stage 54 are larger than in female tadpoles at the same stage. In tadpoles which developed from eggs irradiated in the vegetal hemisphere with u.v. light at the 2- to 4-cell-stage, primordial germ cells migrate into the genital ridges much later (stage 46–48) than in unirradiated embryos. They also differ morphologically from germ cells in control animals at this stage in that they are approximately one-tenth the size, lacking yolk in the cytoplasm and have a more highly lobed nucleus. Comparison of the results in unirradiated and irradiated animals suggests that the germ cell lineage is composed of a series of ordered, predictable events, and serious disruption of one of the events deranges later events.

Relationship between the amount of the ‘germinal plasm’ and the number of primordial germ cells in Xenopus laevis

Development ◽  
1974 ◽  
Vol 31 (1) ◽  
pp. 89-98
Author(s):  
Kazuyuki Tanabe ◽  
Minoru Kotani
Keyword(s):  
Xenopus Laevis ◽  
Germ Cell ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
The Other ◽  
Direct Proportion ◽  
Sensitive Material ◽  
Cell Stage ◽  
Other Hand ◽  
Germinal Plasm

Tadpoles of Xenopus laevis completely lacking primordial germ cells were obtained by irradiating the vegetal hemisphere of early 2-cell eggs with u.v. (wavelength, 253·7 nm; dose, ca. 6000 ergs/mm2). An increasing number of primordial germ cells were observed as the stage at irradiation advanced from early 2-cell to early 4-cell stages. Furthermore, early 2-cell eggs irradiated with doses ranging from 750 to 6000 ergs/mm2 grew into tadpoles carrying a decreasing number of primordial germ cells in accord with the increase of the dose. On the other hand, tadpoles developed from eggs irradiated immediately after being centrifuged at 150 g for 1 min at early 2-cell stage to displace the ‘germinal plasm’ deeper into the cytoplasm, carried a considerable number of primordial germ cells. These facts were interpreted to suggest the presence of u.v.-sensitive germ cell determinant in the ‘germinal plasm’. It was revealed by varying the area of irradiation that the number of primordial germ cells decreased in direct proportion to the increase of the area irradiated. It was concluded that the amount of the u.v.-sensitive material(s) contained in the ‘germinal plasm’ determined the number of primordial germ cells in tadpoles.

scholarly journals Ligand–Receptor Interactions Elucidate Sex-Specific Pathways in the Trajectory From Primordial Germ Cells to Gonia During Human Development

2021 ◽  
Vol 9 ◽  
Author(s):  
Arend W. Overeem ◽  
Yolanda W. Chang ◽  
Jeroen Spruit ◽  
Celine M. Roelse ◽  
Susana M. Chuva De Sousa Lopes
Keyword(s):  
Germ Cell ◽  
Signaling Pathways ◽  
Germ Cells ◽  
Tyrosine Kinases ◽  
Intracellular Localization ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Systematic Analysis ◽  
Receptor Interactions

The human germ cell lineage originates from primordial germ cells (PGCs), which are specified at approximately the third week of development. Our understanding of the signaling pathways that control this event has significantly increased in recent years and that has enabled the generation of PGC-like cells (PGCLCs) from pluripotent stem cells in vitro. However, the signaling pathways that drive the transition of PGCs into gonia (prospermatogonia in males or premeiotic oogonia in females) remain unclear, and we are presently unable to mimic this step in vitro in the absence of gonadal tissue. Therefore, we have analyzed single-cell transcriptomics data of human fetal gonads to map the molecular interactions during the sex-specific transition from PGCs to gonia. The CellPhoneDB algorithm was used to identify significant ligand–receptor interactions between germ cells and their sex-specific neighboring gonadal somatic cells, focusing on four major signaling pathways WNT, NOTCH, TGFβ/BMP, and receptor tyrosine kinases (RTK). Subsequently, the expression and intracellular localization of key effectors for these pathways were validated in human fetal gonads by immunostaining. This approach provided a systematic analysis of the signaling environment in developing human gonads and revealed sex-specific signaling pathways during human premeiotic germ cell development. This work serves as a foundation to understand the transition from PGCs to premeiotic oogonia or prospermatogonia and identifies sex-specific signaling pathways that are of interest in the step-by-step reconstitution of human gametogenesis in vitro.

scholarly journals Purification of mouse primordial germ cells by Nycodenz

Reproduction ◽  
2003 ◽  
pp. 667-675 ◽  
Author(s):  
T Mayanagi ◽  
R Kurosawa ◽  
K Ohnuma ◽  
A Ueyama ◽  
K Ito ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Specific Antibody ◽  
Membrane Surface ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Specific Antigen ◽  
Cell Lineage ◽  
New Method ◽  
Purification Method

Primordial germ cells are important cells for the study of germ cell lineage. It has proved difficult to obtain highly purified primordial germ cells for preparation of a specific antibody. In the present study, a new method for purifying mouse primordial germ cells was developed using a Nycodenz gradient. Furthermore, the polyclonal anti-mouse primordial germ cells IgG derived from mouse primordial germ cells was prepared. As this IgG reacted only with primordial germ cells obtained at day 12.5 after mating, this antibody appeared to recognize the stage-specific antigen of primordial germ cells. One reason that a continuous primordial germ cell marker has not been obtained is because the purity of the primordial germ cells used has been too low to prepare the antibody. This new method represents a significant improvement in the purification of primordial germ cells; it is simpler than previous methods, and produced mouse primordial germ cells with a purity of more than 95%. In addition, the separation reagent Nycodenz is non-toxic and achieved separation of primordial germ cells without attachment of antibodies against the primordial germ cell membrane surface. This new purification method and stage-specific antibody will be useful for the analysis of the mechanisms of primordial germ cell migration.

scholarly journals Functional reconstruction of NANOS3 expression in the germ cell lineage by a novel transgenic reporter reveals distinct subcellular localizations of NANOS3

Reproduction ◽  
2010 ◽  
Vol 139 (2) ◽  
pp. 381-393 ◽  
Author(s):  
Masashi Yamaji ◽  
Takashi Tanaka ◽  
Mayo Shigeta ◽  
Shinichiro Chuma ◽  
Yumiko Saga ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Regulatory Elements ◽  
Initiation Factor ◽  
Processing Bodies

Mutations of RNA-binding proteins such as NANOS3, TIAL1, and DND1 in mice have been known to result in the failure of survival and/or proliferation of primordial germ cells (PGCs) soon after their fate is specified (around embryonic day (E) 8.0), leading to the infertility of these animals. However, the mechanisms of actions of these RNA-binding proteins remain largely unresolved. As a foundation to explore the role of these RNA-binding proteins in germ cells, we established a novel transgenic reporter strain that expresses NANOS3 fused with EGFP under the control of Nanos3 regulatory elements. NANOS3–EGFP exhibited exclusive expression in PGCs as early as E7.25, and continued to be expressed in female germ cells until around E14.5 and in male germ cells throughout the fetal period with declining expression levels after E16.5. NANOS3–EGFP resumed strong expression in postnatal spermatogonia and continued to be expressed in undifferentiated spermatogonial cells in adults. Importantly, the Nanos3–EGFP transgene rescued the sterile phenotype of Nanos3 homozygous mutants, demonstrating the functional equivalency of NANOS3–EGFP with endogenous NANOS3. We found that throughout germ cell development, a predominant amount of  NANOS3–EGFP co-localized with TIAL1 (also known as TIAR) and phosphorylated eukaryotic initiation factor 2α, markers for the stress granules, whereas a fraction of it showed co-localization with DCP1A, a marker for the processing bodies. On the other hand, NANOS3–EGFP did not co-localize with Tudor domain-containing protein 1, a marker for the intermitochondrial cements, in spermatogenic cells. These findings unveil the presence of distinct posttranscriptional regulations in PGCs soon after their specification, for which RNA-binding proteins such as NANOS3 and TIAL1 would play critical functions.

Replacement of posterior by anterior endoderm reduces sterility in embryos from inverted eggs of Xenopus laevis

Development ◽  
1986 ◽  
Vol 94 (1) ◽  
pp. 83-93
Author(s):  
J. H. Cleine
Keyword(s):  
Cell Differentiation ◽  
Xenopus Laevis ◽  
Germ Cell ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Inverted Position ◽  
Control Series ◽  
Germ Cell Differentiation ◽  
Tailbud Stage

The genital ridges of Xenopus laevis tadpoles reared from eggs kept in an inverted position contain less than 40 % of the number of primordial germ cells (PGCs) of controls (Cleine & Dixon, 1985). It has been suggested that this reduction is caused by the germ cells' ectopic position in the anterior endoderm of larvae from inverted eggs, from where they may be unable to migrate into the genital ridges (Cleine & Dixon, 1985). This hypothesis is tested here by interchanging anterior and posterior endodermal grafts between pairs of inverted embryos at the early tailbud stage. Replacement of anterior by posterior endoderm has no effect but replacement of posterior by anterior endoderm increases the number of PGCs in the genital ridges and significantly reduces the proportion of sterile embryos. In a control series, in which the same type of grafting was done with normal embryos, replacement of posterior by anterior endoderm reduced the number of germ cells to almost zero, but replacement of anterior by posterior endoderm nearly doubled it. These findings are explained in terms of the distribution of the germ cells in the endoderm at the time of grafting. The results firstly show that the position of the germ cells is crucial to successful migration and secondly they support the notion that germ plasm has a determinative role during early germ cell differentiation.

The effect of u.v. irradiation of the vegetal pole of Xenopus laevis eggs on the presumptive primordial germ cells

Development ◽  
1975 ◽  
Vol 34 (1) ◽  
pp. 209-220
Author(s):  
Brigitta Züst ◽  
K. E. Dixon
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Initial Effect ◽  
Vegetal Pole ◽  
Cortical Regions ◽  
The Individual

The initial effect of u.v. irradiation of the vegetal pole was to inhibit cleavage in the vegetal hemisphere although karyokinesis was not substantially affected. In this way a syncytium formed in the vegetal hemisphere which broke down into individual cells some time between morula and late blastula. The movement of the germ plasm from the peripheral cortical regions into the interior of the egg was not appreciably delayed although aggregation of the germ plasm did not take place until the individual presumptive primordial germ cells were formed when the syncytium broke down. The method of segregation of the germ plasm and formation of the presumptive primordial germ cells was therefore very different in irradiated embryos from the normal orderly processes which depend on normal cleavage patterns. After neurula, the number of presumptive primordial germ cells declined rapidly and at stage 43/44, when the genital ridges in normal embryos contain primordial germ cells, the genital ridges in irradiated embryos were sterile. These results raise the question whether derangement of the segregation of the presumptive primordial germ cells is solely responsible for the later abnormalities in the cell lineage or whether u.v. irradiation affects the germ plasm and therefore indirectly the germ cells.

Cytological analyses of factors which determine the number of primordial germ cells (PGCs) in Xenopus laevis

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 251-265
Author(s):  
Yasuko Akita ◽  
Masami Wakahara
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Cell Stage ◽  
Unknown Mechanism ◽  
Fertilized Egg ◽  
Number Of Cells ◽  
Experimentally Induced

Correlation of the number of primordial germ cells (PGCs) at stage 47 with the amount of germ plasm at the 8-cell stage and with the number of the germ-plasm-containing cells (GPCCs) was analysed using two different laboratory-raised colonies of Xenopus laevis, HD and J groups. The average number of PGCs in J group tadpoles was significantly larger than that in HD group tadpoles. The amount of germ plasm in J group embryos was also demonstrated to be larger than in HD group embryos. The amount of germ plasm was related positively to the number of GPCCs at the 8-cell stage and to the resulting number of PGCs; embryos which contained larger amounts of germ plasm developed larger numbers of PGCs at stage 47. The average number of PGCs in experimentally induced triploid tadpoles was exactly twothirds of that in normal diploid tadpoles. Furthermore, in somatic cells (e.g. epidermis, muscle, pancreas), the number of cells in the triploid was also two-thirds of that in diploid tadpoles. These findings suggest that the number of PGCs is regulated by at least two different mechanisms: first, the number of PGCs is primarily specified by the intrinsic amount of germ plasm in the fertilized egg. Second, it is regulated by an unknown mechanism which controls the total number of cells of whole embryos, such as the nucleocytoplasmic ratio.

Germ-cell transfer and sex ratio in Xenopus laevis

Development ◽  
1965 ◽  
Vol 13 (1) ◽  
pp. 51-61
Author(s):  
A. W. Blackler
Keyword(s):  
Xenopus Laevis ◽  
Germ Cell ◽  
South African ◽  
Germ Cells ◽  
Sexual Differentiation ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Hormone Treatment ◽  
Sex Reversal ◽  
Cell Transfer

A Technique for the transfer of primordial germ cells between neurulae of the South African Clawed Toad Xenopus laevis has been described by Blackler & Fischberg (1961). This method was originally developed with the object in mind of eventually making a genetic analysis of abnormal embryos resulting from the transplantation of somatic nuclei. Such analysis involves two schemes which require the transfer of embryonic gonocytes from the defective transplant embryo to a normal recipient. Moreover, one of these two schemes requires that transferred germ cells be reversed in their sexual differentiation in the developing gonad of the host (see Fischberg, 1961; Fischberg & Blackler, 1963a, b). Since it has been known for some time, from experiments involving parabiosis, transplantation of the gonadal rudiment and hormone treatment (e.g. Burns, 1925, 1930; Witschi, 1937; Humphrey, 1929, 1933, 1948, 1957; Gallien, 1953, 1956), that the manifestation of the sex genotype of a primordial germ cell can be physiologically reversed by the hormonal characteristics of the gonad, there seemed no obstacle to obtaining sex-reversal of the transferred gonocytes in Xenopus.

Zebrafish vasa homologue RNA is localized to the cleavage planes of 2- and 4-cell-stage embryos and is expressed in the primordial germ cells

Development ◽  
1997 ◽  
Vol 124 (16) ◽  
pp. 3157-3165 ◽  
Author(s):  
C. Yoon ◽  
K. Kawakami ◽  
N. Hopkins
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Germ Line ◽  
Genetic Manipulation ◽  
Primordial Germ Cells ◽  
Specific Protein ◽  
Northern Blotting ◽  
Model Organisms ◽  
Specific Marker ◽  
Cell Stage

Identification and manipulation of the germ line are important to the study of model organisms. Although zebrafish has recently emerged as a model for vertebrate development, the primordial germ cells (PGCs) in this organism have not been previously described. To identify a molecular marker for the zebrafish PGCs, we cloned the zebrafish homologue of the Drosophila vasa gene, which, in the fly, encodes a germ-cell-specific protein. Northern blotting revealed that zebrafish vasa homologue (vas) transcript is present in embryos just after fertilization, and hence it is probably maternally supplied. Using whole-mount in situ hybridization, we investigated the expression pattern of vas RNA in zebrafish embryos from the 1-cell stage to 10 days of development. Here we present evidence that vas RNA is a germ-cell-specific marker, allowing a description of the zebrafish PGCs for the first time. Furthermore, vas transcript was detected in a novel pattern, localized to the cleavage planes in 2- and 4-cell-stage embryos. During subsequent cleavages, the RNA is segregated as subcellular clumps to a small number of cells that may be the future germ cells. These results suggest new ways in which one might develop techniques for the genetic manipulation of zebrafish. Furthermore, they provide the basis for further studies on this novel RNA localization pattern and on germ-line development in general.

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